Hydraulic breaking hammer

ABSTRACT

A hydraulic breaking hammer having a machine housing including a cylinder bore and an impact piston which is reciprocatingly movable in the cylinder bore in response to an alternating hydraulic pressure, and a tool part having: (i) a head portion fitted to a front portion of the machine housing, and (ii) a guide bore which lies in line with the cylinder bore and in which a breaking tool is slidably carried and repeatedly subjected to impact by the impact piston. A seal is arranged at the front portion of the machine housing between the cylinder bore and the impact piston for separating drive hydraulics of the breaking hammer from the tool part, and a transverse slot is formed in the front portion of the machine housing between mutually opposing side wall portions of the machine housing so as to intersect the cylinder bore forwardly of the seal. A plurality of lateral bores extend through the side wall portions of the machine housing and the head portion of the tool part, respectively, on both sides of the guide bore of the tool part, and a plurality of retainers are provided for locking the tool part to the machine housing when the retainers are inserted in respective ones of the lateral bores.

BACKGROUND OF THE INVENTION

The present invention relates to hydraulic breaking hammers of the kindthat comprise a machine housing which includes a cylinder bore and areciprocatingly movable impact piston which moves backwards and forwardsin said cylinder bore in response to alternating hydraulic pressure, atool part which is fitted to the front of the machine housing and whichhas a guide bore which lies in line with the cylinder bore and in whicha breaking tool is slidably carried and repeatedly subjected to impactby the impact piston as it moves, support means for aligning thebreaking hammer mechanically in operation, and sealing means arranged inthe front of the machine housing between the cylinder bore and theimpact piston and functioning to separate the drive hydraulics of thebreaking hammer from the tool part.

Breaking hammers of this kind are normally mounted on hydraulicallyoperated carriers of different sizes, wherein the carrier hydraulics arealso coupled to drive the breaking hammer, and wherein the breakinghammer is pivotally mounted on the outer end of a boom via the supportson said housing so as to be positioned mechanically by said boom inoperation.

The machine housing of the breaking hammer is typically comprised ofseparate cylinder parts which embrace the impact piston, the seals andthe valve system, and which are grouped axially in juxtaposedrelationship and held tightly together by robust side bolts, so as toensure that a seal is obtained between the cylinder parts against thehigh internal hydraulic working pressures. Side bolts and other screwfastener means, however, have certain drawbacks. The screw threads areshaken loose. In the case of side bolts, the wear and the corrosion thatoccurs in operation, together with micro-movements in the joints as aresult of impacts and vibrations generated in the breaking hammer, causethe joints of the cylinder parts and their seals to be attacked bypenetrating pressure oil and leakages and ultimately result inconditions which are hazardous both to the surroundings and to people inthe vicinity of the work being carried out. Side bolts can alsofracture, with serious consequences. In recent times, this insight intothe hazards of side bolts has led to an endeavour to exclude side boltsfrom breaking hammer constructions. An example of one such endeavour isdisclosed in International Publication WO 93/22106, PCT/SE93/00382.

Lightweight automotive carriers and short breaking hammers have beenused in the demolition of derelict buildings, so as to be able to enterconfined spaces more easily and to work therein more effectively. Thehydraulic part of the machine housing forms the rear part of thebreaking hammer and can therewith readily be made short and sufficientlyrobust to provide a long useful life, in the absence of side bolts.However, indoor demolition work results in an increase in laterallyacting impacts, blows and breaking action, particularly against thebreaking tool and against the tool part at the front of the housing,such that after being in operation for some length of time, the entiremachine housing may be judged to be ineffective due to damage to thetool part. This is highly disadvantageous from the cost aspect, in viewof the fact that the hydraulic part of the tool is expensive to produceand cannot be considered as being a spare part.

OBJECT OF THE INVENTION

With regard to hydraulic breaking hammers of the type concerned here, anobject of the invention is to provide a breaking hammer which is betteradapted for indoor demolition work and which has a front part or toolpart which eliminates the need for side bolts and which also enables thelonger useful life of the hydraulic part mounted in the machine housingto be used more effectively. The novel design of the tool part alsoenables the tool part to be exchanged quickly and easily when servicingthe hammer, and also provides for better accessibility to the interiorof the machine housing and reduces the centering requirement between thetool part and the machine housing. The novel mounting of the tool partin the machine housing also enables transmission of impact forces fromthe tool part to the machine housing to be dampened during hammeroperation.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described in more detail with reference to theaccompanying drawings, in which;

FIG. 1 illustrates an inventive breaking hammer from above;

FIG. 2 is a cross-sectional view taken on the line 2--2 in FIG. 1;

FIG. 3 is an isolated view of the tool part in FIG. 1 from above;

FIG. 4 is a side view of the tool part shown in FIG. 3;

FIG. 5 is a longitudinal section view taken on the line 5--5 in FIG. 1;and

FIG. 6 is a view corresponding to FIG. 2 illustrating a modification ofthe tool part attachment.

DETAILED DESCRIPTION

The breaking hammer 10 shown in FIG. 1 includes a machine housing 11 anda tool part 16 which is fitted to the front of the housing 11. The toolpart slidably carries a breaking tool 18, which is detachably retainedin the guide bore 21 of said tool part 16 by means of locking retainers33 (FIG. 5) and which has limited axial movement in the guide bore 21.The locking retainers 33 coact with recesses 35 provided in the breakingtool 18, and are insertable into lateral bores 34 in the tool part 16.The machine housing 11 carries at its rear end two supports 25 whichinclude bores, indicated at 32, for pivotal connection to an automotivecarrier (not shown), conveniently a lightweight carrier for buildingdemolition purposes, and with a hydraulically operable boom formechanical alignment of the breaking hammer 10 in the process of itswork. The tool part 16 has a pointed or tapering configuration whichenables the tool to work effectively and to reach into confined cornersin demolition and cleaning operations.

The machine housing 11 also contains a cylinder bore 12 and areciprocatingly movable impact piston or ram 15 which moves backwardsand forwards in said bore in response to alternating hydraulic pressuresdelivered through the medium of a distributing valve bore 14, FIG. 5.The hydraulics used to drive the impact piston may have, in principle,any suitable known design, for instance may be slide-guided as describedin the aforesaid publication WO 93/22106 and need not therefore bedescribed here. The breaking hammer hydraulics are mounted in theinterior of the machine housing and are held separate from the tool part16 by seal 13 provided at the front end of the machine housing 11 anddisposed around the front end of the impact piston 15. The cylinder bore12 is sealed-off at its rear end by means of a cover plate 37 bolted tothe rear end of the housing 11. The housing 11 is robust and made in onesingle piece from cast iron, including the supports 25.

Similar to the cover plate 37, the tool part 16 is carried by themachine housing 11 without the aid of side bolts or any othervibration-sensitive screw-threaded devices. To this end, the forwardpart of the machine housing 11 forms mutually parallel and mutuallyopposing side-wall parts 22 between which there extends a transverseslot 23 which intersects the cylinder bore 12 forwardly of the sealingmeans 13. Rearwardly of the locking retainers 33, the tool part 16 formsa head 17 which extends transversely to the guide bore 21 and which fitsslidingly in and can be inserted between the side-wall parts 22, so thatthe guide bore 21 will be in alignment with the cylinder bore 12. Thehead 17 is provided with through-penetrating lateral-bores 20 on eachside of the guide bore 21, and the side-wall parts 22 includelateral-bores 19 which are located coaxially with the lateral-bores 20when the head 17 is fitted between the side-wall parts 22. Whenretainers 26, 27 are inserted through the lateral-bores 19, 20, there isobtained a robust attachment of the tool part 16 to the machine housing11, wherein the tool attachment can be made and unmade both quickly andeasily.

In a simplified form, the lateral-bores 19, 20 can be made identical toone another and accommodate single retainers or, as indicated in FIG. 1,lengthwise divided retainers in direct metal to metal contact in thelateral-bores 19, 20 of the side-wall parts 22 and the head 17, as shownin FIGS. 2 and 6. However, the retainer attachment between the aforesaidparts can be used very conveniently to dampen vibrations. In thisregard, the retainers 26, 27 are fitted with impact-damping plasticsleeves 29, at least in the lateral-bores 20 in the head 17, theselateral-bores being given a slightly larger diameter than thelateral-bores 19 so as to provide room for the sleeves 29. The sleeveswill preferably be made of polyurethane, which affords a good vibrationdamping effect. It will be seen from FIGS. 1 and 5 that when the toolpart 16 is inserted and secured by the retainers, gaps 39, 40 are formedbetween the bottom of the lateral slot or channel 23 and adjacentside-wall parts 22 and the head 17 and its adjacent end-walls 38. Due tothe vibration-space in the gaps 39, 40, the plastic sleeves 29 are ableto dampen occurrent impacts and prevent the transmission of impactforces to the machine housing 11 as a result of direct metallic contact.

In the case of the FIG. 2 embodiments, the retainers are cylinder andare slit along an undulating line 36 so as to form tensioning bushes 26which press against the lateral-bores 19 and secure the retainerslongitudinally against being shaken out from the bores while thehydraulic breaking hammer is in use. The retainers are preferably madefrom steel and are radially resilient.

In the case of the FIG. 6 embodiment, the solid steel retainers 27include a circular groove 30 in the region of the sleeves 29.Correspondingly, the sleeves 29 are provided with an internal bead 31which springs into the circular groove as the retainers 27 are fitted.Due to the differences in the diameters of the cross-bores 19, 20, thesleeve 29 and its bead 31 will hold the retainers 27 locked in positionin the head 17 of the tool part 16 located between the side-wall parts22 of the machine housing 11.

It will be observed that the construction does not require the impactpiston 15 to be accurately centered in the guide bore 21 of the toolpart 16. The impact piston 15 may simply lie in the guide bore andrepeatedly strike against the breaking tool 18 with free play in saidguide bore 21, to no disadvantage.

I claim:
 1. A hydraulic breaking hammer comprising:a machine housingincluding a cylinder bore and an impact piston which is reciprocatinglymovable in said cylinder bore in response to an alternating hydraulicpressure; a tool part having: (i) a head portion fitted to a frontportion of said machine housing, and (ii) a guide bore which lies inline with said cylinder bore and in which a breaking tool is slidablycarried and repeatedly subjected to impact by said impact piston; a sealarranged at said front portion of said machine housing between saidcylinder bore and said impact piston for separating drive hydraulics ofsaid breaking hammer from said tool part; a transverse slot formed insaid front portion of said machine housing between mutually opposingside wall portions of said machine housing so as to intersect saidcylinder bore forwardly of said seal; a plurality of lateral boresextending through said side wall portions of said machine housing andsaid head portion of said tool part, respectively, on both sides of saidguide bore of said tool part; and a plurality of retainers for lockingsaid tool part to said machine housing when said retainers are insertedin respective ones of said lateral bores.
 2. The hydraulic breakinghammer according to claim 1, further comprising impact-damping plasticsleeves fitted at least between said retainers and said head portion ofsaid tool part, and wherein at least one gap is formed between mutuallyopposing surfaces of said machine housing and said tool part when saidhead portion of said tool part is locked to said machine housing.
 3. Thehydraulic breaking hammer according to claim 2, wherein a diameter ofsaid lateral bores in said head portion of said tool part is greaterthan a diameter of said lateral bores in said side wall portions of saidmachine housing, and wherein said impact-damping plastic sleeves arefitted around said retainers in said head portion of said tool part. 4.The hydraulic breaking hammer according to claim 3, wherein saidretainers comprise hollow cylinder bushes which are slotted along anundulating line and which exert a radially and outwardly acting force.5. The hydraulic breaking hammer according to claim 3, wherein saidretainers each comprise a solid member having a circular groove in aregion of said impact-damping plastic sleeves, and wherein saidimpact-damping plastic sleeves each include an internal bead whichsprings into said solid groove of a respective one of said retainers tolock the respective one of said retainers between said side wallportions of said machine housing.
 6. The hydraulic breaking hammeraccording to claim 2, wherein a front portion of said tool part includesat least one lateral bore for detachably receiving a locking retainerwhich together with lateral recesses provided on said breaking toollocks said breaking tool in said tool part while limiting axial movementof said breaking tool in said tool part.
 7. The hydraulic breakinghammer according to claim 2, wherein said at least one gap comprises agap formed at a bottom portion of said lateral slot.
 8. The hydraulicbreaking hammer according to claim 7, wherein said at least one gapfurther comprises a gap formed adjacent to said side wall portions ofsaid machine housing.
 9. The hydraulic breaking hammer according toclaim 2, wherein said impact-damping plastic sleeves comprisepolyurethane sleeves.
 10. The hydraulic breaking hammer according toclaim 1, wherein said guide bore of said tool part is adapted toaccommodate said impact piston with a given clearance.